Field of the Invention
The invention lies in the field of household appliances. The invention relates to a method for determining the loading weight of a laundry drum in a washing machine or in a washer dryer, the drum being driven directly by an electric motor controlled by an electronic control or regulating device, and to an electric machine in the form of a washing machine or a washer dryer for carrying out a method according to the invention.
The prior art includes a washing machine with a laundry drum that is driven about a horizontal axis of rotation by an electric motor and that has a closable loading aperture disposed on its periphery. The laundry drum can be loaded with laundry when it stops in a rotational position at which the loading aperture is at the top. An electronic control or regulating device for controlling the electric motor that drives the drum is configured such that it always stops the drum in the rotational position at which its loading aperture is at the top.
German Published, Non-prosecuted Patent Application DE 44 31 846 A1 discloses a method for controlling and/or regulating a washing machine or a washer dryer. The method is used for a laundry drum when the drum is rotating at a speed at which the laundry comes to rest in a manner distributed around the inner circumference. The method is also used to calculate the unbalance of laundry distributed in a non-uniform manner around its circumference of the drum. Further, the method is used to calculate the total weight of the laundry (loading) contained in the laundry drum and to control or regulate as a function of these two values the speed of a motor that drives the laundry drum. The method is carried out with the laundry drum loaded (filled with laundry) when the drum is rotating at least at a xe2x80x9cspreading speed.xe2x80x9d The xe2x80x9cspreading speedxe2x80x9d is the speed of the laundry drum at which the laundry distributes itself around the inner circumference of the drum. While the laundry drum is starting up, high unbalance torques can occur because they are not taken into account. The method furthermore requires a complicated and expensive electronic device for detecting angular accelerations of the laundry drum.
German Published, Non-prosecuted Patent Application DE 195 46 185 A1, corresponding to U.S. Pat. No. 5,809,809, discloses a washing machine having a laundry drum that is driven directly by an electric motor rather than through a drive belt. As such, a rotor of an electric motor is connected firmly in terms of rotation to a drive shaft of the laundry drum, and the stator of the electric motor is secured non-rotatably on the rear wall of the laundry drum housing (washing-liquid container). Precise synchronism between the motor and the laundry drum is thereby achieved.
It is accordingly an object of the invention to provide a method for determining the loading weight of a laundry drum and a laundry-processing machine for carrying out the method that overcomes the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and that precisely determines the loading of the laundry drum (the weight of the laundry contained in the laundry drum) in a simple and economical manner, even when the machine is not rotating at the operating speed, and that can be used for any desired purpose, in particular, for indicating the loading weight and/or for controlling or regulating the speed and/or acceleration of the laundry drum and/or the duration of processing of the batch of laundry in the laundry drum.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for determining a loading weight of a horizontally mounted laundry drum, including the steps of providing a laundry drum driven by an electric motor controlled by a controller, the laundry drum having an axis of rotation, directly driving the laundry drum with the electric motor, turning the laundry drum with the electric motor from a 0xc2x0 angular position, in which laundry is lying in a lower position in the laundry drum, through a rotational angle until reaching an angular position at which the laundry is in a raised position and at which a center of gravity of the laundry is at a lateral distance from a vertical plane extending through the axis of rotation, detecting the reaching of the angular position with the controller, and producing a measured value corresponding to a loading weight of the laundry from a driving current of the electric motor measured when the angular position is reached.
With the objects of the invention in view, there is also provided a method for determining a loading weight of a horizontally mounted laundry drum, including the steps of providing a laundry drum driven by an electric motor controlled by a controller, the laundry drum having an axis of rotation, directly driving the laundry drum with the electric motor, storing a predetermined, defined maximum current value in the controller, measuring a power consumption of the electric motor, rotating the laundry drum with the electric motor out of a 0xc2x0 angular position, in which laundry lies in a lower position in the laundry drum, until the controller detects, during the rotation of the laundry drum, a power consumption of the electric motor corresponding to the stored maximum current value, the rotation resulting in a raising of the laundry into a position in which a center of gravity of the laundry is at a lateral distance from a vertical plane extending through the axis of rotation, and the rotation resulting in an angular traveling of the laundry drum to an angular distance from the 0xc2x0 angular position, and producing a measured value corresponding to a loading weight of the laundry from a signal corresponding to the angular distance.
In accordance with another mode of the invention, the electric motor receives and transmits at least one of power consumption signals and control signals, and further includes the steps of producing the control signals with the controller dependent on angular positions of a rotor of the electric motor relative to a stator of the electric motor, and defining or calculating with the controller an angular distance through which the laundry drum is turned from the 0xc2x0 angular position to reach the angular position at which the loading weight of the laundry is determined by the controller using fluctuations in at least one of the power consumption signals and control signals.
In accordance with a further mode of the invention, the laundry drum is part of a washing machine or a washer/dryer.
In accordance with an added mode of the invention, the controller is an electronic control or regulating device.
In accordance with an additional mode of the invention, the electric motor is an electronically commutated d.c. motor, and further includes the step of defining or calculating the angular distance or position using a number of commutation steps from the 0xc2x0 angular position of the laundry drum to the angular position at which the loading weight is determined.
In accordance with yet another mode of the invention, the electric motor is an electronically controlled reluctance motor.
In accordance with yet a further mode of the invention, there are also provided the steps of detecting an angular position of the laundry drum with a tachogenerator as a function of angular movements of the laundry drum to produce electric pulses, and measuring angular distance traveled with a number of the electric pulses.
With the objects of the invention in view, there is also provided a washing appliance, including a stationary component, a laundry drum rotatably mounted on the stationary component about a horizontal axis of rotation, the drum moving through a 0xc2x0 angular position, in which laundry is lying in a lower position in the laundry drum, and through an angular position at which the laundry is in a raised position and at which a center of gravity of the laundry is at a lateral distance from a vertical plane extending through the axis of rotation, an electric motor directly connected to the laundry drum for driving the laundry drum, a controller connected to the electric motor, the controller configured to determine a loading weight of the laundry drum when the laundry drum is turned with the electric motor from the 0xc2x0 angular position to the angular position by measuring an electric driving current of the electric motor at the angular position to produce a measured value corresponding to the loading weight of the laundry.
With the objects of the invention in view, there is also provided a washing appliance, including a stationary component, a laundry drum rotatably mounted on the stationary component about a horizontal axis of rotation, the drum moving through a 0xc2x0 angular position, in which laundry is lying in a lower position in the laundry drum, and through an angular position at which the laundry is raised and at which a center of gravity of the laundry is at a lateral distance from a vertical plane extending through the axis of rotation, an electric motor directly connected to the laundry drum for driving the laundry drum, and a controller connected to the electric motor for detecting a power consumption of the electric motor and having a stored predetermined, defined maximum current value, the controller configured to determine a loading weight of the laundry drum when the laundry drum is driven from the 0xc2x0 angular position stored in the controller until the controller detects during rotation of the laundry drum that a power consumption of the electric motor corresponds to the stored maximum current value, and to measure an angular distance traveled from the 0xc2x0 angular position for producing a measured value corresponding the loading weight of the laundry.
In accordance with yet an added feature of the invention, the appliance one a washing machine or a washer/dryer.
In accordance with a concomitant feature of the invention, the controller is an electronic control or regulating device.
The invention achieves its objectives by implementing measurement of loading in a simple and economical manner on a laundry-processing machine. The results of the measurement are accurate enough to be used as parameters in control or regulation of the laundry-processing machine. A laundry-processing machine equipped in accordance with the invention avoids the dry movement of the laundry in the laundry drum, which is required by prior art methods and involves considerable wear on the laundry due to severe friction between the fibers resting upon one another.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for determining the loading weight of a laundry drum and a laundry-processing machine for carrying out the method, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.